CN104100909B - A Design Method of Adaptive Headlamp Based on Fly-eye Lens - Google Patents

Abstract

The invention discloses a method for designing an adaptive headlight based on a fly-eye lens. In the field of automotive headlights, existing technologies have shortcomings such as inaccurate control of light and low utilization of light energy. The present invention includes a projection part and a reflection part. In the projection part, a parabolic reflector and a collimator lens are used to collimate the light emitted by the LED, and then a double-row fly-eye lens and a converging lens are used to uniformly image the beam on a digital micromirror. Each row of fly-eye lenses consists of three small lenses of different shapes. The beneficial effects of this design scheme are: accurate control, multiple lighting modes and good effects of various lighting modes; separate realization of high beam and low beam to reduce heat dissipation difficulty; use fly-eye lens to form uniform and bright light on the digital micromirror The light spot with light and dark cut-off line saves light energy and improves the utilization rate of light energy; double-row fly-eye lens is used as the uniform light system, which has a short optical path and good light uniform effect.

Description

A Design Method of Adaptive Headlamp Based on Fly-eye Lens

technical field

The invention relates to the technical field of an automobile headlight, in particular to a design method for an adaptive headlight based on a fly-eye lens.

Background technique

Adaptive Front Lighting System (AFS, Adaptive Front Lighting System) can timely and automatically adjust the light pattern of the headlight, the distance of the light beam and the intensity of the brightness according to the changes of the surrounding environment, and provide a more suitable lighting range, lighting distance and lighting angle . The adaptive headlights are equipped with lighting modes such as high beam, low beam, curve, uphill and downhill, town road, high speed, rain and snow weather. The curve lighting mode provides enough illumination for curves by controlling the horizontal rotation angle of the headlights and eliminates the dark areas of the curves; the uphill and downhill lighting modes control the vertical deflection angle of the headlights to increase the field of vision when going uphill or reduce the Glare on slopes; the urban road mode outputs a wider light pattern, which increases the lighting width and increases the driver's field of vision; the high-speed mode outputs a narrower and longer light pattern, improves the lighting depth, and meets the needs of vehicles driving at high speeds; rain and snow The weather lighting mode reduces the illumination in some areas and reduces the glare caused by the reflection of the ground water on the human eye.

There are three implementation schemes for existing adaptive headlights: 1. Dynamic AFS; 2. Static LED dot-matrix AFS; 3. Digital Micromirror (DMD) AFS.

The Chinese patent with the publication number CN102069749A discloses a dynamic AFS, which uses a sensor group to collect changes in the surrounding environment, and then uses a stepper motor to control the deflection of the headlights in the horizontal and vertical directions to achieve an adaptive function, but the dynamic In addition to the traditional high beam and low beam, AFS mainly realizes the lighting modes of curves and uphill and downhill. There are few lighting modes that can be realized, and it still needs to cooperate with other solutions to fully realize the adaptive function.

The Chinese patent with the publication number CN103419709A discloses a static LED dot-matrix AFS. In this scheme, multiple LEDs are arranged into an LED array, and different lighting modes are realized by controlling the luminous power of each LED on the array. However, due to the large number of LEDs Many, if one LED is damaged, the entire AFS cannot work normally, and this solution has the disadvantages of difficult assembly adjustment and inaccurate light control.

The Chinese patent with the publication number CN102705767A discloses a digital micromirror AFS. In this scheme, the light is evenly irradiated on the digital micromirror element after passing through the rectangular light guide tube, and the micromirror on the digital micromirror element is controlled. Flip position (±12°) and flip frequency to achieve different lighting modes. However, this solution has the following defects: (1) Both the low beam and the high beam are realized by digital micromirror elements, but the low beam requires a wider beam and a relatively uniform illuminance distribution, while the high beam requires concentrated light and a longer range. For example, in the adaptive headlight standard "UNIFORM PROVISIONS CONCERNING THE APPROVALOFADAPTIVE FRONT-LIGHTING SYSTEMS (AFS) FORMOTORVEHICLES (ECER123)" promulgated in Europe, the illuminance value of the HV point should be less than 0.7lux at low beam, and at least 38.4lux at high beam . Therefore, when the parameters of the light source and the lens are unchanged, only using the micromirror on the digital micromirror element to realize the near beam and the high beam will cause defects such as low light utilization rate, difficult heat dissipation, and poor far and near beam effects. (2) For low beam, high-speed, urban road and rainy and snowy weather lighting modes, it is necessary to form a light spot with a clear cut-off line on the light screen, and in this scheme, a 16:9 digital micromirror element is formed Or a rectangular spot of 4:3, it can be known by calculation that only 51.88% or 53.6% of the micromirrors on the digital micromirror element are in the "ON" state (+12°), and nearly half of the micromirrors are in the "OFF" state ( -12°), which not only increases the workload of the digital micromirror element chip but also wastes a large amount of light energy. (3) The rectangular light pipe has a long optical path and poor light uniformity effect, which will increase the volume of the system and reduce the control accuracy.

Therefore, in the adaptive headlight technology, there is an urgent need for a system that realizes multiple lighting modes and good effects of various modes, precise control, high light energy utilization rate, low heat dissipation difficulty, and a light uniform system with a short optical path and good uniform light effect. optical scheme.

Contents of the invention

In order to solve the above technical problems, the present invention provides a fly-eye lens-based adaptive headlamp design method.

A design method of self-adaptive headlights based on fly-eye lens, including projecting part and reflecting part, in curves and up and down slopes, stepping motor is used to control the deflection of the headlights at a certain angle in the horizontal and vertical directions; the projecting part is used for Realize low beam, high-speed, urban road and rain and snow weather lighting functions; reflective part is used to realize high beam function.

In the projection part, a parabolic reflector and a collimating lens are used to collimate the light emitted by the LED, and then the light is irradiated onto the digital micromirror element after passing through a double-row fly-eye lens.

Establish an xyz coordinate system, the z-axis is parallel to the ground and points to the front of the car, the x-axis is parallel to the ground and perpendicular to the z-axis, and the y-axis is perpendicular to the ground; choose LED light source 2 with a half divergence angle of θ as the light source for the projection part, parabolic reflection The reflection surface of the device satisfies: x ² +z ² =2py(-2p≤x≤2p, $\frac{p+2{\mathrm{ptan}}^2\mathrm{\θ}-2p\mathrm{the\; tan}\mathrm{\θ}\sqrt{1+{\mathrm{the\; tan}}^2\mathrm{\θ}}}{2}\≤\mathrm{the\; y}\≤2p,$ z≤0).

The second LED light source is located at the focus of the parabola (0, 0), the semicircular collimator lens with focal length f ₁ is located at (0, 0), its optical axis coincides with the y-axis.

Each row of fly-eye lenses is composed of M rows×N columns of small lens units, and the two refraction surfaces of each small lens unit are respectively a plane and a spherical surface with a radius of curvature r, the refractive index is n, and its focal length is f2=r/( n-1), the distance between the front row and the rear row of lenses is equal to f2; there are small lenses of three shapes in each row of fly-eye lenses, the first row of lenses is obtained by removing a trapezoid from the lower left of the rectangular lens, the second row to the M-th The first row of lenses is obtained by removing a trapezoid from the lower left and upper right of the rectangular lens, and the last row of lenses is obtained by removing a trapezoid from the upper right of the rectangular lens.

The long and short width of each lenslet are respectively and , and the ratio is 16:4.5 or 4:1.5; the angle of the inclined part in the small lens is 45 degrees or 135 degrees or 215 degrees.

A compound parabolic concentrator, a curved light pipe and a plano-convex lens 2 are used to collect the light reflected by the micromirror in the "OFF" state of the digital micromirror element and project it to the lower right of the light distribution screen.

Compared with the existing technology, the beneficial effects of this design method are: precise control, multiple lighting modes and good effects of various lighting modes; separate implementation of high beam and low beam, reducing the difficulty of heat dissipation; using fly-eye lens in the digital A uniform light spot with cut-off line is formed on the micromirror element, which saves light energy and improves the utilization rate of light energy; the double-row fly-eye lens is used as the light uniform system, which has a short optical path and good light uniform effect.

Description of drawings

Figure 1 is a schematic diagram of an adaptive headlight.

Fig. 2 is a schematic diagram of the projection section.

Fig. 3 is a schematic diagram of three different shapes of small lenses in a fly-eye lens.

FIG. 4 is a schematic diagram of an 8×6 fly-eye lens array.

Fig. 5 is a schematic diagram of a double-row fly-eye lens.

Fig. 6 is a uniform light spot diagram with a cut-off line on the digital micromirror element.

Fig. 7 is a low beam light pattern diagram formed on the light distribution screen 25 meters away from the car lamp.

In the figure 1. Projection part, 2. Reflection part, 3. Free-form surface, 4. Mirror, 5. LED light source 1, 6. Parabolic reflector, 7. LED light source 2, 8. Collimating lens, 9. Front row Fly eye lens, 10. Rear fly eye lens, 11. Converging lens, 12. Digital micromirror element, 13. Compound parabolic concentrator, 14. Curved light pipe, 15 plano-convex lens 1, 16. Plano-convex lens 2, 17 Light distribution screen, 18. A small lens in the first row of fly-eye lenses, 19. A small lens in the middle part of fly-eye lenses, 20. A small lens in the last row of fly-eye lenses, 21.8×6 fly-eye lens array.

detailed description

Describe specific implementation below in conjunction with accompanying drawing and example.

Figure 1 is a schematic diagram of an adaptive headlight. It is composed of a projection part and a reflection part. When turning and going up and down slopes, a stepping motor is used to control the lights to deflect at a certain angle in the horizontal and vertical directions; the projection part contains a digital micromirror and a fly-eye lens for low beam and high-speed , urban roads and rainy and snowy weather lighting functions; the reflective part contains LED light sources and free-form reflectors to realize the high beam function. In the reflective part, the LED light source is evenly distributed on the cylindrical lamp holder, and there is a reflector at the front end of the cylindrical lamp holder, which can reflect the light directly emitted without passing through the reflector to the reflector.

Fig. 2 is a schematic diagram of the projection section. In the reflector design for the projected part, establish Coordinate System, axis parallel to the ground and pointing straight ahead of the car, Axis parallel to the ground and perpendicular to axis, The axis is perpendicular to the ground; the half divergence angle is selected as The LED light source 2 is used as the light source of the projection part, and the curved surface of the parabolic reflector satisfies: ( , , ), in order to save space, the part that cannot be reached by the LED light at the rear of the parabola and the right half of the parabola are cut off. LED light source 2 is located at the focus of the parabola (0, , 0), the focal length is The semicircular collimator lens is located at (0, ,0), its optical axis and Axis coincidence is used to collimate beams that cannot hit the reflector surface.

The collimated light is irradiated onto the digital micromirror element after passing through the double-row fly-eye lens, forming a uniform light spot with cut-off line on the digital micromirror element. The micromirror in the "ON state" in the digital micromirror element irradiates the light to the screen at a distance of 25 meters; the micromirror in the "OFF" state in the digital micromirror element cannot reflect the light to the screen. (CPC), curved light pipe and plano-convex lens II collect it and project it to the lower right of the light distribution screen at a distance of 25 meters. The system realizes four lighting modes, which are ClassC (low beam), ClassV (urban road), ClassE (high-speed) and ClassW (rain and snow) in the self-adaptive headlight standard "UNIFORMPROVISIONSCONCERNINGTHEAPPROVALOFADAPTIVEFRONT-LIGHTINGSYSTEMS (AFS) FORMOTORVEHICLES (ECER123)". weather).

Double-row fly-eye lens is adopted, and each row of fly-eye lens is composed of Line× A column of small lens units. Fig. 3 is a schematic diagram of three different shapes of small lenses in a fly-eye lens. The first row of small lenses is obtained by cutting out a trapezoid from the bottom left of the rectangular lens, as shown in the upper left corner (a) of Figure 3. The small lenses from the second row to the M-1th row are obtained by cutting out a trapezoid from the lower left and upper right of the rectangular lens, as shown in the upper right corner (b) of Figure 3. The last row of lenses is obtained by cutting out a trapezoid from the upper right of the rectangular lens, as shown in the lower left (c) of Figure 3. The angle of the inclined portion in the lenslet is 45 degrees or 135 degrees or 225 degrees.

FIG. 4 is a schematic diagram of an 8×6 fly-eye lens array. The two refraction surfaces of each small lens unit are respectively a plane and a spherical surface with a radius of curvature r, the refractive index is n, and its focal length is , the distance between front and rear lenses ; The long and short width of each lenslet are and , and in order to match with the digital micromirror element, the ratio of the length of the small lens to the shorter width is 4:1.5. Although in this embodiment, the aspect ratio of the small lens is 4:1.5, the aspect ratio of the small lens is also 16:4.5.

Figure 5 is a schematic diagram of a double-row fly-eye lens. The light is irradiated parallel to the double-row fly-eye lens after passing through a reflector and a collimating lens. Imaging, after passing through the converging lens, the image of the small light source is superimposed on the digital micromirror element.

Fig. 6 is a light spot diagram on a digital micromirror element that is uniform and has a cut-off line. The light spot on the digital micromirror element is uniform and has a cut-off line.

Figure 7 is a diagram of the low-beam light pattern formed by the car lights on the light distribution screen 25 meters away. In the figure, the low-beam light pattern has a clear cut-off line and various special points (such as B50L, 75R, etc.) and special areas (Such as Zone I, Zone III, etc.) are in line with the adaptive headlight standard "UNIFORM PROVISIONS CONCERNING THE APP PROVALOFA DAPTIVE FRONT-LIGHTING SYSTEMS (AFS) FORMOTORVEHICLES (ECER123)". For high-speed, urban road and rainy and snowy weather lighting functions, it can also be realized by controlling the flip position (±12°) and flip frequency of the micromirror on the digital micromirror element.

The above-mentioned embodiments only illustrate the principles and functions of the present invention, and some of the embodiments. For those of ordinary skill in the art, some modifications and improvements can be made without departing from the inventive concept of the present invention. These all belong to the protection scope of the present invention.

Claims (1)

1. A method for designing adaptive headlights based on a fly-eye lens, including a projection part and a reflection part. When turning and going up and down slopes, a stepping motor is used to control the car lights to deflect at a certain angle in the horizontal and vertical directions. Its characteristics Yes: the projection part is used to realize low beam, high-speed, urban road and rain and snow weather lighting functions; the reflective part is used to realize high beam function; In the projection part, a parabolic reflector and a collimating lens are used to collimate the light emitted by the LED; the light then passes through a double-row fly-eye lens and then irradiates the digital micromirror element; Establish an xyz coordinate system, the z-axis is parallel to the ground and points to the front of the car, the x-axis is parallel to the ground and perpendicular to the z-axis, and the y-axis is perpendicular to the ground; choose LED light source 2 with a half divergence angle of θ as the light source for the projection part, parabolic reflection The reflecting surface of the device satisfies: $x^2+z^2=2p\mathrm{the\; y}(-2p\≤x\≤2p,\frac{p+2{\mathrm{ptan}}^2\mathrm{\θ}-2pta\mathrm{no}\mathrm{\θ}\sqrt{1+{\mathrm{the\; tan}}^2\mathrm{\θ}}}{2}\≤\mathrm{the\; y}\≤2p,$ $z\≤0);$ The second LED light source is located at the focus of the parabola , the semicircular collimating lens with focal length f ₁ is located at , its optical axis coincides with the y-axis; Each row of fly-eye lenses is composed of M rows×N columns of small lens units, and the two refraction surfaces of each small lens unit are respectively a plane and a spherical surface with a radius of curvature r, the refractive index is n, and its focal length is f2=r/( n-1), the distance between the front row and the rear row of lenses is equal to f2; there are small lenses of three shapes in each row of fly-eye lenses, the first row of lenses is obtained by removing a trapezoid from the lower left of the rectangular lens, the second row to the M-th The first row of lenses is obtained by removing a trapezoid from the lower left and upper right of the rectangular lens, and the last row of lenses is obtained by removing a trapezoid from the upper right of the rectangular lens; The long and short width of each lenslet are respectively and And the ratio is 16:4.5 or 4:1.5; the angle of the inclined part in the small lens is 45 degrees or 135 degrees or 215 degrees; A compound parabolic concentrator, a curved light pipe and a plano-convex lens 2 are used to collect the light reflected by the micromirror in the "OFF" state of the digital micromirror element and project it to the lower right of the light distribution screen.